Effects of interfacial contact under different operating conditions in proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis (PEMWE) cells have made significant progress with regards to their performance, durability and cost reduction in the past few decades. Although the interfacial contacts between each PEMWE cell component have a significant impact on cell performance and durability, their effects are still not fully investigated. In this study, the interfacial contact between porous transport layers (PTLs) and catalyst layers (CLs) is systematically studied utilizing various test protocols and conditions, including step scan, dynamic sweep scan, galvanostatic and potentiostatic control. Poorly designed electrical contact at the anode PTL/CL interface will lead to an increased electrical resistance, and results in a high frequency resistance (HFR) and dependency on current density. In addition, the data suggest that an uncoated PTL/CL interfacial contact causes an inhomogeneous temperature distribution on the micro-scale, which may accelerate cell degradation. Improving the interfacial contact by applying platinum group metal coatings, such as thin film Ir coatings, reduces the cell ohmic resistance and improves the heat management. This study gives insights into the effects of interfacial contacts, test protocols and impact on operation conditions. The impact of PTL microstructure as function of PTL thickness is elucidated. It emphasizes the importance of an optimized interfacial contact and provides guidelines for PEM electrolysis measurement protocols.